Question

Problem Statement:  An urban circumferential freeway is to be designed on the basis of the following information: design year average annual daily traffic, AADT = 75,000 veh/day; the estimate of the percent of traffic occurring during the peak-hour is 9%; the percent of peak-hour traffic in the heavier direction is estimated to be 55%. The traffic mixture is expected to be similar to the current mixture of 7% trucks, 3% buses and no recreational vehicles. The PHF is estimated to be 0.9. The base free-flow speed is 70 mph. If the freeway is to be built on rolling terrain with no lateral obstructions and 12-ft lanes, determine the number of lanes needed to provide a minimum LOS of B.

1) (3 pts) Describe in 1 to 3 complete sentences:

• What type of problem is this?
• Describe what you are being asked to solve for.
• Draw a diagram of the problem.

2) (3 pts) Describe, in complete sentences, the general method used for solving the type of problem identified in step a.

3) (2 pts) List all know information, translated into the appropriate variables. For example, if the problem specifies, “the initial speed is 70-mph”, you would list this as v_i=70 mph.

4) Solve the problem, explaining each step. You should explain what each step is, why you are using a particular equation, any assumptions you are making. You should split your paper in half vertically and use one side to write the solution and the other side for the explanation. An example of what I’m looking for in a setup is below.

5) (2 pts) In 1 to 2 complete sentences, provide an analysis or justification for your solution. Does the answer seem reasonable? Why or why not? Is it the right order of magnitude? Why or why not?

Answer 1

This is a numerical problem in which number of lanes required for urban freeway are calculated such that freeway can be operated at LOS B. All the other data were given. All the steps for calculations are already shown and are self explanatory.

The problem is solved using the procedure laid in Highway Capacity Manual for Freeways.

The total number of lanes required to accomadate AADT= 75000 veh / day are coming to be 8, which is a realastic figure. For lesser OR more than 8 lanes LOS B wi not be maintained.